Field of the Invention
The present invention relates to a damping force controlling shock absorber, and more particularly, to a damping force controlling shock absorber, in which a pilot passage and a bypass passage are shared between a cut-out portion formed in a hollow of a pilot disk and a branch groove of a spool guide, thereby simplifying a passage structure, simplifying a passage adjustment structure of a spool, and improving productivity and dispersion of products.
Description of the Related Art
In general, a shock absorber is installed in means of transportation, such as automobile or the like, and improves ride comfort by absorbing and damping a vibration or shock transferred from a road surface during driving.
Such a shock absorber includes a cylinder and a piston rod installed to be compressible and extendable within the cylinder. The cylinder and the piston rod are coupled to a vehicle body, wheels, or axles.
A shock absorber, a damping force of which is set to be low, can improve ride comfort by absorbing a vibration caused by unevenness of a road surface during driving. On the contrary, a shock absorber, a damping force of which is set to be high, can improve steering stability by suppressing a change in a posture of a vehicle body.
Therefore, there has been developed a damping force controlling shock absorber in which a damping force controlling valve capable of appropriately adjusting damping force characteristics is mounted on one side thereof, such that the damping force characteristics are appropriately adjusted to improve ride comfort or steering stability according to a road surface and a driving condition.
In general, such a conventional damping force controlling shock absorber has a structure to select a hard passage and a soft passage by selectively opening and closing a plurality of passages formed in a spool guide while changing a position of a spool.
That is, a hard damping force or a soft damping force may be selectively generated by selectively adjusting an opened/closed state of the hard passage and the soft passage formed in the spool guide.
To this end, the conventional damping force controlling shock absorber individually forms the pilot passage for forming the hard damping force and the soft passage for forming the soft damping force.
However, in the conventional damping force controlling shock absorber, since the hard passage and the soft passage are individually formed, the structure of the apparatus becomes complicated and dispersion may occur during mass production. Due to the complicated structure, the assembling of the apparatus is difficult, resulting in an increase in manufacturing costs.
As the prior art document related to the present invention, Korean Patent Application Laid-Open No. 10-2009-0003019 (Jan. 9, 2009) discloses a damping force controlling shock absorber.